1. Field of the Invention
The present invention relates to a printing apparatus. In particular, the present invention is suitable for a printing apparatus including an open/close lid that closes or opens a conveyance path of a recording paper.
2. Description of the Related Art
Conventionally, printing apparatuses based on various systems are proposed as a means for printing an image to a recording paper. With the printing apparatus, a paper feed unit feeds and conveys a recording paper for printing an image, and a printing unit therein prints the paper. The printing apparatus includes an opening for externally discharging the printed recording paper after conveying the recording paper via a paper conveyance path downstream.
In particular, the number of compact printers with high portability is recently increased. The usage environment of the printer is not limited to the indoors, furthermore, the compact printer is available with an attachable battery without requiring the plug-in connection via a cable when supplying electrical power. Therefore, the printing apparatus needs to be structured in consideration of the outdoor use. Specifically, when the opening portion, from which the recording paper in the printing apparatus is discharged, is always open, dust or a foreign matter can invade the printing apparatus from the opening portion. In particular, when the printing apparatus is carried outside, there is high possibility that sand dust invades the printing apparatus during conveyance.
If the foreign matter invades the printing apparatus, a printing operation is performed in a state in which the foreign matter adheres to the surface of the recording paper. Thus, there is fear that the quality of a printed matter deteriorates, or the printing unit is damaged, so that the printing apparatus can deteriorate earlier. Therefore, there is recently provided a printing apparatus having an openable and closable lid capable of opening or closing an opening portion to prevent a foreign matter from invading. To prevent a recording paper from falling on the floor when the recording paper is externally discharged from the printing apparatus, there is provided a printing apparatus having a paper stacking unit such as a paper discharge tray. Moreover, there is a printing apparatus in which a part of an exterior casing forms a lid having both a function for preventing the foreign matter from invading and a function as the paper discharge tray.
However, if the lid is arranged on the paper conveyance path, when a user carelessly starts the printing operation in a closing state of the lid, and the leading edge of the conveyed recording paper thus collides with the inside of the lid since the paper conveyance path is closed. In this case, there is a problem that the recording paper is not subsequently conveyed, the recording papers are stuck in the printing apparatus, and paper jam occurs.
As a jam preventing mechanism for preventing the jam, there is a technique for detecting the closing state of a paper discharge port by open/close lid with a detection sensor. With the technique, the open/close lid is opened, a detected member is consequently moved from a standby position, and the sensor detects a flag portion of the detected member. The state corresponds to an on-mode for enabling the start and continuation of a printing operation. On the other hand, by closing the open/close lid, the detected member is moved to the standby position, i.e., the position where the detected member is not detected. The state corresponds to an off-mode for disabling the printing operation. Therefore, if carelessly closing the open/close lid during the printing operation, the on-mode for enabling the detection of the detected member is changed to the off-mode for disabling the detection of the detected member, thereby suspending the printing operation.
Further, there is a technique in which the apparatus is configure to includes a biasing solenoid in conjunction with a power supply of an apparatus at an opening portion and a lever operated by energizing the solenoid, and the open/close lid is closed or opened by latching the lever thereto. The lever is rotated by energizing the solenoid at power-on and is retracted from a hook portion of the open/close lid with which the lever is engaged. Then, the latching is released and the opening portion is simultaneously opened by a spring which is biasing the open/close lid in the direction of opening the lid.
However, with the configuration including the detection sensor that detects the opening/closing state of the open/close lid, a sensor for detecting the opening/closing state is required independently of a sensor which is necessary for a normal operation. Further, there is a problem that, a circuit for controlling the sensor needs to be additionally provided, thereby increasing in costs and becoming a complicated configuration. Furthermore, there is another problem that, although printing operation is started already, if the user closes the open/close lid since there is not the printed matter in the paper stacking unit, a signal of the sensor turns off state when the open/close lid is closed and the printing operation is suspended.
With the configuration of releasing the lock by energizing the solenoid, the lock is released only at the energization time. Thus, if the user carelessly closes the open/close lid after starting the printing operation, the open/close lid is held in the closing state. Further, if releasing the lock of the open/close lid after starting the printing operation is required, the solenoid needs to be continuously energized. In addition, there is a problem of great increase in costs because the solenoid is used to control the locking operation of the open/close lid.